Optical reticle



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B. STECHB'ART- ,I OPTICAIJIRETICLE May 13, 1947.

Filed Au 51, 1944 5 Sheets-Sheet 1 BRUN ETEEHBART EIY ATTY.

May 1947- B. STECHBART 2,420,503

oP'rxqil p -YETICLE Filed A 31, 1944 3 Sheets-Sheet 2 INVENTUR BRLJNU ETEEHEART BY ATTY.

My 13, 1947. B. STECHBART 2,420,503

OPTICAL RpTicLE Filed. 5331, 1944 s Sheets-Sheet 5 INVENTUR BRUNO. STEEHBART BYW ATTY

Patented May 13, 1 347 '15 Guy I x 2,42o',sos OPTICAL narrow Bruno Stechbart, Park Ridge, 111., assignor to The i Bell & Howell Company, Chicago llll, a corporation of Illinois Application August 31, 1944, Serial No. 552,107

4 Claims. (01. 88-1 Y I My invention relates particularly to optical reticles of the illuminated type from which images 01' the illuminated reticle designs thereof, are projected by projection objectives to provide sighting images. a

Objects of the invention reside in the provision of a novel and effective optical reticle of the above type which provides adequate brilliancy' throughout the projected image of the reticle design thereof, and which promotes uniform brilliancy throughout the projected image.

The invention will be better understood by reference to the accompanying drawing forming a part hereof and in which- Figure 1 is a face elevational view of an optical reticle embodying one form of my invention;

Figure 2 is an opposite face elevational view of the same;

Figure 3 is an enlarged sectional view substantially on the line 3-3 of Figure 1;

Figure 4 is a sectional view of the reticle similar to Figure 3 and showing it in cooperating relation with a light source;

Figure 5 is a face elevational view of an optical reticle embodying another form of my invention; 7

Figure 6 is a sectional view substantially on the line 6-5 of Figure 5;

Figure 7 is a fac elevational view of an optical reticle embodying another form of my invention; and I Figure 8 is a partial sectional view substantially on the line B--8 of Figure '7. f

Referring to Figures 1 to 4 inclusive, a body of molded light transmitting material, such optical glass, and of circular disk form is designated at I, and an opaque mask 2 is disposed at one face 3 of the body and as shown comprises a paint coating. The mask is provided with a light opening therethrough in the form of a reticle design pattern, generally designated at i, and radiating from a light axis 5 disposed centrally of and normal to the body I, and as shown this light opening comprises a center light opening portion 6 at the light axis, two annular light opening portions 1 and 8 of different diameters disposed concentrically of the light axis and four light opening portions 9 spaced equiangularly about and extending radially of the light axis, the pattern of the light opening.

except for the center light opening 6, being thus of lineal character.

A condensing lens system, generally designated at H, is formed integrally with and at the opposite face l'2 of the body I, and is in the form of a reticle design pattern corresponding with the pattern of the light opening 4 of the mask and element l4, two annular elements I5 and it of different diameters disposed concentrically of the light axis and four lens elements ll spaced equiangularly about and extending radially of the light axis, these lens elements respectively corresponding and being disposed in optically registering relation with the light opening portions 6, I, ii and 9 of the mask. The lens system, except for the center lens element I4. is thus of. lineal character, and the center lens element I4 is of convex hemispherical form and the lens elements l5, l6 and I1, being of lineal character,

are of convex semi-circular cross section- 'The condensing lens system II has the convexly surface face thereof facing the light source l3, and the radii of the convex surface curyae ture and the lateral extent of the several---pof- As shown, the convexly surface face of thecondensing lens system, which faces the light source, defines a concave surface of revolution of the light axis and facing the light source, as designated at i8 in Figures 3 and 4, which provides for the proper focal relation of the several portions of the condensing lens system with the flat light opening of the mask, it being also observed that this arrangement also causes the light from the light source to desirably impinge on the radially extending lens elements I! at angles approximating or approaching ninety degrees in axial planes of the light axis.

To illustrate, in Figures 3 and'4, the light paths from the light source through the condensing lens system and to the light opening of the mask at the centerlight opening portion 8, at the smaller annular light opening portion 1 and at the larger annular light opening portion 8, are respectively designated at I9, 20 and 2|, it being observed that the area of the light concentrated increases outwardly from the light axis.

Referring to Figures 5 and 6, a reticle, substantially the same as that of Figures 1 to 4, comprises a body 22 of light transmitting material and of circular disk form, an opaque mask 23 disposed ,at one face of the body and provided with a light opening therethrough in the form of a reticle design pattern, generally designated at 24, and radiating from the light axis 25, and a condensing lens system 26 formed integrally with and at the opposite face of the body and in the form of a reticle design pattern corresponding with the pattern of the light opening 24 and radi ating from the light axis and disposed in optically registering relation with pattern of the light opening for concentrating light thereat from a light source on and spaced along the light axis from the body 22 and consequently from the mask and condensing lens system.

are a 5 lateral extent of the several portions of the lens system are uniform throughout the condensing lens system, thus beingof more simple form though lacking the advantage of the promotion of uniform brilliancy of illumination of the pattern of the light opening.

The reticle of Figures 5 and 6 functions in the j same manner as that of Figures 1 to 4, and is quite similar thereto with the exception that, instead of the convexly surfaced face of the coniidensing lens system defining a concave surface of revolution of the reticle axis as in Figures 1 to 4, the convexly surface face 21 of the condensing lens system of Figures 5 and 6 defines an internal frusto-conical surface of revolution of the light axis and facing the light source, the frusto-conical surface of revolution being of more simple form though it is less optically correct in that it only approximates the more optically correct concave surface of revolution.

Referring to Figures 7 and 8, a reticle, generally the same as those of Figures 1 to 4 and Figures 5 and 6, comprises a body 28 of light transmitting material and of circular disk form, an opaque mask 29 disposed at one face of the body and provided with a light opening therethrough in the form of a reticle design pattern, generally designated at so, and radiating from the light axis 3|, and a.condensing lens system 32 formed integrally with and at the opposite face of the body and in the form of a reticle design pattern corresponding with the pattern of the light open ing 30 and radiating from the light axis and disposed in optically registering relation with the pattern of the light opening for concentrating light thereat from a light source on andspaced along the light axis from the body 28 and consequently from the mask and condensing lens system.

The reticle of Figures '7 and 8 functions in the it While I have thus described my invention, I do not Wish to be limited to the precise details described, as changes may be readily made without departing from the spirit of my invention, but having thus described my invention, I claim as new and desire to secure by Letters Patent the following:

1. In an optical reticle, the combination of a 1 body of light transmitting material and of disk form, a mask at one face of said body and provided with a light opening therethrough in the form of a reticle design pattern, and a condensing lens system formed integrally with and at the reticle design pattern corresponding with the pattern of said light opening and disposed in optically registering relation therewith for concentrating light thereat. I 1

2. In an optical reticle, the combination of a body of light transmitting material and of disk form,'a mask at one face of said body and provided with a light opening therethrough in the form of a reticle design pattern of lineal character, and a condensing lens system formed integrally with and at the opposite face of said body and in the form of a reticle design pattern of lineal character corresponding with the pattern of said light opening and disposed in optical ly registering relation therewith for concentrating light thereat and comprising lineal portions of convex part circular cross section. g,

3. In an optical reticle, the combination of a body of light transmitting material and of disk form, a mask at one face of said body and provided with a light opening therethrough in the form of a reticle design pattern radiating from an axis disposed centrally of and normal to said body, and a condensing lens system formed integrally with and at the opposite face of said body and in the form of a reticle design pattern corresponding with the pattern of said light opening and radiating from said axis and 'disposed in optically registering relation with the pattern of said light opening for concentrating thereat light received from along said axis and the radii of the convex surface curvature and the lateral extent of the several portions of said lens system increasing outwardly from said .raxis.

4. In an optical reticle, the combinati'dri' of a body of light transmitting material and of disk form, a mask at one face of said body and provided with a light opening therethrough in the -"form of a reticle design pattern radiating from an axis disposed centrally of and normal to said body, and a condensing lens system formed insame manner as those of Figures 1 to 4 and Figtegrally with and at the opposite face of said body and in the form of reticle design pattern corresponding with the pattern of said light opening and radiating from said axis and disposed in optically registering relation with the pattern of said light opening for concentrating thereat light received from along said axis and having the convexly surfaced face thereof facing said received light and arranged to define at least approximately a concave surface of revolution opposite face of said body and in the form of a of said axis and facing said received light and Number the radii of the convex surface curvature and the 1,918,705 lateral extent of the several portions of said lens 1,992,608 system increasing outwardly from said axis. 2,271,196 BRUNO STECHBAR'I. 5 #692,973 U ,r;'1,646,292 REFERENCES CITED 540,184

The following references are of record in the file of this patent: 1o e UNITED STATES PATENTS Number Name Date 33? 533,324 Stevens Jan, 29, 1895 1 1,475,430 Curwen Nov. 27, 1923 6 Name Date Ives July 18, 1933 -Deninson Feb. 26, 1935 Kaszab Jan. 27, 1942 Babcocl: Nov. 27, 1928 Hough Oct. 18, 1927 Norris May 28. 1895 Fordyce Nov. 17, 1936 Rose Aug. 27, 1929 FOREIGN PATENTS Country Date Great Britain Oct. 28,1935

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